How to improve heart rate tracking accuracy?

[Amanda_UK]

I do the same workout three times in a row, exact same, yet my fitbit is showing wildly different results on each one. The first time I was in cardio range most of the time, which makes sense and it said I burned 275 cals, second time it said I was in fat burn the whole time!! and only 150 cals, third time I compared it to another heart rate monitor that said I was in cardio most of the time but my sense still said I was only around 99 beats per min average, that is IMPOSSIBLE. I am very frustrated at this expensive piece of jewelry on my wrist please help!

It seems to be very much under counting the heart rate. I tried restarting, tightening, cleaning it, moving to correct position during exercise. What else can I do. Will a factory reset help? How can I do that? Right now it is pointless even wearing it tbh.

[JohnnyRow]

We have no idea what type workout you were doing.  Some activities make it notoriously difficult to get good heart rate measurements with optical wrist sensors, including activities with lots of wrist movements and vibrations, such as some weight-lifting  movements, punching bag, hockey, etc.  In addition to looking at totals, it might help to look at heart rate graph for total time to see if it is fluctuating wildly like it might be losing contact with arm.  Also might try loosening band so can wear it higher up arm further away from wrist. Supposedly there is more blood flow further up the arm and can get better readings there, though maybe not as convenient for glancing at time throughout the day.

[Guy_]

Hi @Amanda_UK - have you tried wearing the watch on a chest strap, due to the more stable environment you may find a greater all round accuracy.

[Amanda_UK]

I was walking and running, and I already tried moving positions on the wrist as stated in my op. Also, do you know how to set stride length? I tried looking up how to do it as I saw other posts saying it was something we were supposed to do in the past, but can't find any instructions. I when I walk my fitbit sense over estimates my calorie burn by a large amount. 

[JohnnyRow]

Phone app Today screen gear icon at top right > Settings: Activity & Wellness > Exercise > Stride Length

This is used just to convert number of steps to distance when not using GPS, such as treadmill or everyday activities.  Fitbit set default separate walking and running stride lengths based on height and other factors which are generally quite close but you can adjust these to your own situation.  FYI, exercise "treadmill" always uses walking stride length even when running.

[Amanda_UK]

I only walk and run outdoors, never treadmills. ATM it is on 'Set Automatically', but the calories it thinks I burn is very inaccurate, over estimating by a huge amount. Maybe it would be better to enter it manually, do you know the easiest way to I find out what my stride length is? The app just says 'If you know your stride length, enter the values here' with no info about how to find out what your stride length is. If I find a track where a mile is measured and count my steps is that the best way?

I never had this problem with my Ionic, which I liked much more than the sense.

[JohnnyRow · Accepted solution]

I don't think stride length would affect calorie burn; that comes from heart rate.  Stride length is just used to convert steps to distance when not using GPS, but shouldn't affect calorie burn.  But if you ever do want to check it, a quarter mile track is probably the best way, or if you have a measured route you regularly run, but it's tough to measure consistently as stride length will vary depending on speed, hills, how tired or fresh you are, etc.  I've expect the default is as close as most people will get unless special situations.

Sorry I don't have any better help for you.

[Amanda_UK]

Thank you. I think I'll try a different strap, I would just like the HR to be more accurate. Your reply was helpful

[JohnnyRow]

If you have ever tried a chest strap monitor, that is the way to get good heart rate reading during exercise as it is reading the electrical signals right from the heart, I think everyone agrees more reliable than the optical reading of wrist monitors though they have come a long way.  But the trouble is  some find them uncomfortable.  And definitely not good for all-day wear.

Unfortunately Fitbit does not accept input from chest straps, as many user wish it would, but some other brands do.  I think many Garmin models do.  That might be something for you to consider, depending on how deeply you are tied to Fitbit with the data you have here.  With another system such as Garmin I think, if you are serious enough to learn the ins and out of a new system, you could wear wristband similar to Fitbit all day, but also a chest strap just for workouts and have it transmit heart rate data to your watch during your workouts.

[Guy_]

@Amanda_UK- before trying another wrist strap have a look at using a chest strap extension for less than $10 it may give you some better results.

I have been testing it with my Sense for the Sleep app [which measures your sleep position] and Sports clock face [which is rotated and enlarged for use on the chest] and got some interesting improvements in accuracy for things like steps, HR, floors, etc. so may be worth a try. It can even work well over a shirt.

My Sense on the wrist can normally display double the HR at times during exercise and other people's watches under read due to the repetitive hand movements.

[Amanda_UK]

@Guy_ Thank you so much! I am going to try this

[Amanda_UK]

@JohnnyRow thank you, I would like to stay with Fitbit as I have about 10 years of data on this account, so I am going to try making the chest extension, but I may switch to Garmin eventually. My husband loves his Garmin stuff.

[JohnnyRow]

@Guy_  Despite all the hardware description of that strap and connectors, the basic concept is still not obvious to me.  Is the idea that you can wear a Fitbit optical sensor as you would an electrical sensor on a chest strap?  And is it to sense the blood flow through the blood vessels the same as it does on the wrist, rather than the electrical signal of the normal chest strap sensors?  Wouldn't that make it very sensitive to exact placement, such as wearing on ankle is very sensitive  to getting placement very precise.  Or are you using a normal chest strap sensor and somehow getting the signal to Fitbit?

[Guy_]

@JohnnyRow - it's wearing the Fitbit anywhere on your chest/tummy, even over a shirt.

It actually works better than on the wrist, if you scroll to the bottom of the page there is a compatible clock face for all Versa and Sense models.

The SimpleSports clock face can be rotated to be worn on wrist, arm or chest and has enlarged values to make it easier to see.

The SimpleSleep app only works on a Versa or a Sense, the only 2 watch models with the hardware needed.